Re: BUG #13427: postgres.exe fails to start on Korean Windows Server 2008: cannot perform encoding conversion outsid

On Wed, Jun 10, 2015 at 02:32:35PM +0000, Dmitri(dot)Bourlatchkov(at)software(dot)dell(dot)com wrote:
> PostgreSQL version: 9.4.3
> Operating system: Windows Server 2008 (Korean)

> 0. Log in as a local Administrator into a Korean version of the Windows
> Server 2008
> 1. Install PostgreSQL 9.4.3 using the Windows .exe installer from
> EnterpriseDB
> 2. Open cmd.exe shell
> 3. cd to potgresql/bin directory
> 4. Run postgresql.exe (no args)
> 5. Observe the following error message:
>
> ----
> FATAL: XX000: cannot perform encoding conversion outside a transaction
> LOCATION: pg_do_encoding_conversion, src\backend\utils\mb\mbutils.c:360
> ----
>
> A similar message shows up when using pg_ctl.exe to start PostgreSQL.

Thanks for this report. One can reproduce this without Korean-specific OS
configuration by setting LC_CTYPE=Korean in the environment and then, as you
say, running postgres without arguments. Stack trace:

postgres.exe!errfinish(int dummy, ...) Line 412
postgres.exe!elog_finish(int elevel, const char * fmt, ...) Line 1376
postgres.exe!pg_do_encoding_conversion(unsigned char * src, int len, int src_encoding, int dest_encoding) Line 362
postgres.exe!pgwin32_message_to_UTF16(const char * str, int len, int * utf16len) Line 1081
postgres.exe!write_console(const char * line, int len) Line 2111
postgres.exe!write_stderr(const char * fmt, ...) Line 3592
postgres.exe!SelectConfigFiles(const char * userDoption, const char * progname) Line 4297
postgres.exe!PostmasterMain(int argc, char * * argv) Line 802

Commit 49c817e is the proximate cause. On my Windows Server 2008 system,
Korean is the only locale affected. It's affected because pg_enc2name_tbl
lacks a UHC <-> CP949 mapping. I'll double check, but adding that mapping
should fix this particular test case.

That leaves other ways of reaching this error. I think e.g. an LC_CTYPE=C,
ENCODING=LATIN9 database will still take this path. Any EmitErrorReport() can
run pgwin32_message_to_UTF16(), and those have plenty of ways to run outside a
transaction. I am inclined to restore the 9.3 and earlier semantics by having
pgwin32_message_to_UTF16() proceed, when outside a transaction, as though the
string is already UTF8. A robust fix would be to cache enough information
about the message encoding to convert outside a transaction, exactly the way
we protect database<->client encoding conversions. That feels more like a
master-only change, though it's a borderline case.

> Trouble-shooting attempted:
> 1. Run set LC_CTYPE=C
> 2. Run postgresql.exe (no args)
> 3. The following expected error shows up:
>
> ----
> Execution of PostgreSQL by a user with administrative permissions is not
> permitted.
> The server must be started under an unprivileged user ID to prevent
> possible system security compromises. See the documentation for
> more information on how to properly start the server.
> ----
>
> Note: PostgreSQL _is_ able to run as a Windows Service without any
> environment modifications.
>
> Note: If the LC_CTYPE=C env. variable is set, PosgreSQL can also be started
> successfully via pg_ctl (under the Administrator user).

That looks normal. pg_ctl has special code in CreateRestrictedProcess() to
drop administrative privileges. To run raw postgres without pg_ctl, use an
unprivileged account or drop privileges similarly in your own wrapper.